In numerous vegetable processing operations, the raw material is preconditioned at cold temperature without removal of the air, subsequent blanching then blocks the enzymatic and microbiological degradations, and the material is then processed into a final product which is frozen or heat pasteurized.
EP482322 (Societe des Produits Nestle S.A.) describes for example a blanching of vegetables and fruits cut into small pieces for 1-15 min at 80-95.degree. C., followed by fermentation with a lactic bacterium at 15-45.degree. C. up to a pH of 3.1-4.4, followed by pasteurization for 2-30 min at 80-110.degree. C.
EP111590 (Frisco-Findus A.G.) describes a process for the preparation of frozen fruits or vegetables producing a reduced volume of waste water consisting in treating the vegetables or fruits in the usual manner up to the blanching stage, in which blanching is carried out by means of steam or a mixture of steam and air, a condensate is recovered, the vegetables or fruits are cooled at least in part by means of air, they are frozen and their surface is glazed with at least part of the condensate produced during the blanching step.
FR 2,638,064 (Guillamot) describes a process for the preparation of purees, cocktails and fruit and vegetable nectars in which whole fruits and vegetables, washed but not peeled, grated or cut, are subjected to blanching and then to enzymatic reactions of 2 h to 24 h using natural proteolytic enzymes and/or enzymes chosen from galactopectases and pectin lyases. This process only makes it possible to increase the solubilization of the solids of protein and pectin origin.
The consequences of a blanching prior to the processing of the material may be unfortunately increased losses of vitamins, flavors, color and texture of the vegetables and/or fruits.
Improvements can be made to the step of blanching a vegetable. FR 2,656,547 (Cogat) thus proposes a continuous blanching apparatus which successively deaerates the material by flushing a neutral gas, heating the materials with steam, keeping the heating temperature constant, and cooling the solids under vacuum by recovering the aromatic condensates. This apparatus makes it possible to limit the oxidative enzymatic degradations during the heating, and to recover the aromatic condensates. The taste, color and texture of the vegetables are thus improved.
Likewise, EP0,124,627 (Frisco-Findus A.G.) proposes a blanching process in which the vegetables are subjected to a first blanching step at 90-100.degree. C. for 1-30 seconds, then to a second blanching step at 45-90.degree. C. for 1-60 min in water. The texture of the treated vegetables is firmer and the color is more intense than those of vegetables treated by conventional blanching.
In spite of all the improvements made to the blanching step, a loss of color, taste and texture of the treated vegetable and/or fruit cannot be avoided.
To overcome this problem, the negative effects of a pasteurization, and the bad natural taste of a juice of sea buckthorn berry (Hyppophae rhamnoides), DE 3,941,555 (VE Forschungsinstitut fur Obst- und Gemuseverarbeitung) proposes disinfecting, with alcohol, fresh sea buckthorn berries and fresh fruits, the fruits preferably having intense flavors, sterilely preparing a mixture of puree of disinfected sea buckthorn berries comprising, in addition, 3-10% of a puree of disinfected fruits or of a juice derived from the fruits, and then preserving it without the presence of air for 24 hours to 6 months at 10-30.degree. C. Blanching of the fruits and of the berries is thus avoided by virtue of the disinfection by the alcohol. A final pasteurization of the mixture is also avoided by virtue of the disinfection and of the acidic pH of the mixture. Finally, it can be noted that the natural "whey" taste of the berries is modified by the enzymes and the flavors of the fruits added.
The present invention aims to avoid a vegetable blanching step, and especially to use the endogenous enzymes of the vegetables to enhance their natural raw flavor and/or taste, as well as their natural color during their processing into juice or puree.